Optimize the additive DAC code, fixing performance-related hangs (#21662)
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7850f0d8c6
commit
1d94de5358
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@ -121,24 +121,27 @@ __attribute__((weak)) uint16_t dac_value_generate(void) {
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/* doing additive wave synthesis over all currently playing tones = adding up
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* sine-wave-samples for each frequency, scaled by the number of active tones
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*/
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uint16_t value = 0;
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float frequency = 0.0f;
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uint_fast16_t value = 0;
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float frequency = 0.0f;
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for (uint8_t i = 0; i < active_tones_snapshot_length; i++) {
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for (size_t i = 0; i < active_tones_snapshot_length; i++) {
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/* Note: a user implementation does not have to rely on the active_tones_snapshot, but
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* could directly query the active frequencies through audio_get_processed_frequency */
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frequency = active_tones_snapshot[i];
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dac_if[i] = dac_if[i] + ((frequency * AUDIO_DAC_BUFFER_SIZE) / AUDIO_DAC_SAMPLE_RATE) * 2 / 3;
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float new_dac_if = dac_if[i];
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new_dac_if += frequency * ((float)AUDIO_DAC_BUFFER_SIZE / AUDIO_DAC_SAMPLE_RATE * 2.0f / 3.0f);
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/*Note: the 2/3 are necessary to get the correct frequencies on the
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* DAC output (as measured with an oscilloscope), since the gpt
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* timer runs with 3*AUDIO_DAC_SAMPLE_RATE; and the DAC callback
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* is called twice per conversion.*/
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dac_if[i] = fmodf(dac_if[i], AUDIO_DAC_BUFFER_SIZE);
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while (new_dac_if >= AUDIO_DAC_BUFFER_SIZE)
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new_dac_if -= AUDIO_DAC_BUFFER_SIZE;
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dac_if[i] = new_dac_if;
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// Wavetable generation/lookup
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uint16_t dac_i = (uint16_t)dac_if[i];
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size_t dac_i = (size_t)new_dac_if;
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#if defined(AUDIO_DAC_SAMPLE_WAVEFORM_SINE)
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value += dac_buffer_sine[dac_i] / active_tones_snapshot_length;
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